A STT-MRAM comprises apparatus, a method of operating and a method of manufacturing a self-referenced magnetoresistive memory and a plurality of magnetoresistive memory element including a self-referenced read scheme through a write/read circuitry coupled to the bit line positioned adjacent to selected ones of the plurality of magnetoresistive memory elements to supply bi-directional spin-transfer recording and reading currents across the MTJ stack. Thus magnetization of a recording layer can be readily switched or reversed to the direction in accordance with a direction of a current across the MTJ stack by applying a spin transfer current, and the magnetization of a reference layer can be readily rotated to two reading directions subsequently in accordance with directions of currents across the MTJ stack by applying low spin transfer currents.
Legal claims defining the scope of protection, as filed with the USPTO.
1. A spin-transfer torque random access magnetoresistive memory (STT-MRAM) comprising a. at least one memory cell, each comprising i. a magnetoresistive memory element comprising: 1. a recording layer having a first magnetic anisotropy and having a switchable magnetization along anisotropy easy axis directions; 2. a tunnel barrier layer adjacent to the recording layer; 3. a soft reference layer adjacent to the tunnel barrier layer, having a variable magnetization direction and having a second magnetic anisotropy; 4. an spin-reading multilayer adjacent to the soft reference layer, comprising a first nonmagnetic spacing layer and a first ferromagnetic or ferrimagnetic layer having a fixed magnetization direction; and 5. an spin-recording multilayer adjacent to the recording layer, comprising a second nonmagnetic spacing layer and a second ferromagnetic or ferrimagnetic layer having a fixed magnetization direction; ii. a bit line atop the magnetoresistive memory element; and iii. a select CMOS transistor coupled the plurality of magnetoresistive memory elements through an electric connection under the magnetoresistive memory element; b. a control circuitry coupled through the bit line and the select transistor to selected ones of the plurality of magnetoresistive memory elements; and c. a recording capability/mechanism/method comprising a data bit is written or recorded as the recording layer magnetization direction is switched along one of anisotropy easy axis directions in the recording layer; and d. a self-referenced reading capability/mechanism/method comprising: i. having that the soft reference layer magnetization in a selected bit is rotated to be parallel to a first anisotropy easy axis direction of the recording layer so that a first magnetoresistance read signal is obtained and stored; ii. having that the soft reference layer magnetization in a selected bit is rotated to be parallel to a second anisotropy easy axis direction of the recording layer so that a second magnetoresistance read signal is obtained and compared to the first magnetoresistance signal; and iii. having that the stored data bit is determined to be a first state as the difference between the first magnetoresistance read signal and the second magnetoresistance signal is positive, and the stored data bit is determined to be a second state as the difference between the first magnetoresistance read signal and the second magnetoresistance signal is negative.
2. The element of claim 1 , wherein said recording layer magnetization is switched by means of the spin-recording layer induced spin transfer torque switching, or spin transfer torque driven domain wall moving along the recording layer.
3. The element of claim 1 , wherein said the soft reference layer magnetization is rotated to be parallel to each anisotropy easy axis direction of the recording layer by means of an external magnetic field, or the spin-reference layer induced spin transfer torque.
4. The element of claim 1 , wherein said second magnetic anisotropy is less than one half of said first magnetic anisotropy, preferred to be less than one fifth of said first magnetic anisotropy.
5. The element of claim 1 , wherein said recording layer and said reference layer have perpendicular anisotropies and a perpendicular magnetizations.
6. The element of claim 1 , wherein said recording layer and said reference layer have anisotropies and magnetizations in film planes.
7. The element of claim 1 , wherein said first optional nonmagnetic spacing layer and said second optional nonmagnetic spacing layer are thin layers of metal materials, preferred to be selected from Cu, Ag, Au, Ru, Rh, or their alloys.
8. The element of claim 1 , wherein said first optional nonmagnetic spacing layer and said second optional nonmagnetic spacing layer are thin layers of metal oxide, metal nitride, metal oxynitride materials, preferred to be selected from MgO, MgN, MgZnO, ZnO, AlOx, AlNx, TiOx, MgTiO, or their doped materials having doping agents, preferred to be selected from Li, Cr, Ta, Ti, Ni, W, Mo, Nb, Hf, Zr, Ru, Al, Cu, Si.
9. The element of claim 1 , wherein said soft reference layer is a multi-layer comprising ferromagnetic sub-layers and optional nonmagnetic insertion sub-layers containing at least one element selected from Ta, Hf, Zr, Ti, Mg, Nb, W, Mo, Ru, Al, Cu, Si and having a thickness less than 0.5 nm.
10. The element of claim 1 , wherein an interface option of said soft reference layer adjacent to the tunnel barrier layer contains a damping constant enhancement doping agent, preferred to be selected from Pt, Pd, Rh, Ir, Ta, Hf, Zr.
11. The element of claim 1 , wherein said recording layer is a multi-layer comprising ferromagnetic sub-layers and optional nonmagnetic insertion sub-layers containing at least one element selected from Ta, Hf, Zr, Ti, Mg, Nb, W, Mo, Ru, Al, Cu, Si and having a thickness less than 0.5 nm.
12. The element of claim 1 , wherein an interface option of said recording layer adjacent to the tunnel barrier layer contains a damping constant enhancement doping agent, preferred to be selected from Pt, Pd, Rh, Ir, Ta, Hf, Zr.
13. The element of claim 1 , wherein said tunnel barrier layer is made of a metal oxide or a metal nitride, a metal oxynitride, preferred to be MgO, ZnO, MgZnO, MgN, MgON.
14. The element of claim 1 , wherein said recording layer further comprises two extended regions from tunnel barrier layer overlaid area and having opposite magnetization directions and electric lead contacts to conduct bi-directional current along said recording layer.
15. The element of claim 1 , further comprising a dielectric functional layer immediately under the stack consisting of said recording layer, tunnel barrier layer and soft reference layer, and comprising a digital line immediately under the dielectric functional layer.
16. The element of claim 15 , wherein said digital line is made of a metal layer or multilayer having a thickness more than 2 nm and less than 2 microns, preferred to have at least one element selected from Ru, Cu, Au, Ag, Al, or other high conductive metal elements.
17. The element of claim 15 , wherein said digital line is made of a metal multilayer having at least one interface layer at the top surface or the bottom surface, preferred to be selected from Ta, TaN, AlN, IrN, or other nano crystal or amorphous materials.
18. The element of claim 15 , wherein said recording layer is a ferromagnetic layer containing Boron, preferred to be CoFeB or CoB, FeB, the Boron composition percentage is preferred to be at least 10%.
19. The element of claim 15 , wherein said dielectric functional layer is made of a metal oxide or a metal nitride, a metal oxynitride having Rocksalt crystalline structures, preferred to be MgO, ZnO, MgZnO, MgN, MgON, has a thickness more than 2 nm.
20. A spin-transfer torque magnetoresistive memory comprising a. at least one memory cell, each comprising i. a magnetoresistive memory element comprising: 1. a recording layer having a first magnetic anisotropy and having a switchable magnetization along anisotropy easy axis directions; 2. a tunnel barrier layer adjacent to the recording layer; and 3. a soft reference layer adjacent to the tunnel barrier layer, having a variable magnetization direction and having a second magnetic anisotropy; ii. a bit line atop the magnetoresistive memory element; and iii. a select CMOS transistor coupled the plurality of magnetoresistive memory elements through an electric connection under the magnetoresistive memory element; b. a control circuitry coupled through the bit line and the select transistor to selected ones of the plurality of magnetoresistive memory elements; and c. a recording capability/mechanism/method comprising a data bit is written or recorded as the recording layer magnetization direction is switched along one of anisotropy easy axis directions in the recording layer; and d. a self-referenced reading capability/mechanism/method comprising: i. having that the soft reference layer magnetization in a selected bit is rotated to be parallel to a first anisotropy easy axis direction of the recording layer so that a first magnetoresistance read signal is obtained and stored; ii. having that the soft reference layer magnetization in a selected bit is rotated to be parallel to a second anisotropy easy axis direction of the recording layer so that a second magnetoresistance read signal is obtained and compared to the first magnetoresistance signal; and iii. having that the stored data bit is determined to be a first state as the difference between the first magnetoresistance read signal and the second magnetoresistance signal is positive, and the stored data bit is determined to be a second state as the difference between the first magnetoresistance read signal and the second magnetoresistance signal is negative.
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February 17, 2014
September 22, 2020
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